Good point Daniel.
The vented Caps have a very small hole in the clear plastic. That could be done with this one but then you are back to what it came with and the chance of water getting into the tank. I would like to find a different way of venting to prevent water infiltration. These work well.
Small down to 1/4" thread screwed into top of tank.
I always put a plastic bag flat on top of the OEM cap and lower the hood on top of the bag when they need to stand out side.

The John Deere 212 thru 216 are the same thread. Took my cap to Fred's & checked on a 214. Not sure how deep the 50 Massey series is, so measure the depth to be sure, but I think these 9" caps would be close enough. The 55 series tanks are about 12" to the top of the filler neck.

The John Deere 212 thru 216 are the same thread. Took my cap to Fred's & checked on a 214. The 55 series tanks are about 12" to the top of the filler neck.

Thats good to know that they will fit.I've been making a new site glass [plastic] for mine every year and expoxying it on.It seems to need to be replaced once a year due to the plastic cracking and yellowing.Now I can go to JD 25 miles from here with a part # in hand and order one ,probably this spring.